Rockwell Automation 1395 Multi-Comm Hardware/Software - Manual (Page 28)

Chapter 3
Configuration & Interfacing
3–17
Discrete PLC Controller
Figure 3–13 illustrates an application where the MCA Board has been
I/O Example
setup for a full rack (numbered rack 2) and the 16 bit words for group 1
and 2 are being used by the PLC Controller program for data transfer with
the Drive. In this example, the Drive has been configured so that the data
coming into source parameter 307 is sent to Logic Cmd 1 (parameter 150).
Information sent to the Drive Using the 16 bit output word for group 1 of
rack 2 must therefore be a 16 bit logic word where the bits are defined by
the description of parameter 150.
In a similar manner, the External Velocity Ref (parameter 154) has been
linked to source parameter 308. The 16 bit output word for group 2 of rack
2 must be a 16 bit signed integer whose value corresponds to the allowable
values in Drive Units for parameter 154.
Information from the Drive consists of Logic Status (parameter 100) and
Velocity Fdbk (parameter 106). Based on the links shown in Figure 3–2,
the 16 bit input word for group 1, rack 2 in the PLC Controller is a 16 bit
logic status word. The bits in this 16 bit word are defined by the
description for parameter 100. In addition, the 16 bit input for group 2,
rack 2 in the PLC Controller is a 16 bit signed integer whose value
corresponds to the allowable values in Drive Units for parameter 106.
If the data transferred between the Drive and PLC Controller will be
manipulated (in the PLC Controller) in units other than Drive Units, the
PLC Controller program must scale the information. The scaled
information must be based on the Drive Units definitions for the
parameters in the Drive. The External Vel Ref (parameter 154) is in Drive
units where 4096 is defined as base speed. If the PLC Controller program
is written in terms of feet per minute (FPM), then FPM must be converted
to Drive Units before being sent to the Drive.